The present invention relates to the formation, processing, and projection or display of wide-gamut-color images. Conventional images, including wide-gamut-color images, are formed using three or more primary colors that are combined in various proportions to form a gamut of colors that include a fraction of the full gamut of all possible colors in nature, fewer than all colors in the full gamut. A primary color is one of a set of colors whose perceived central wavelength is used to define an apex of a polygon or surface that defines the gamut of colors represented by the set of primary colors. In the limit, as the number of “primary” colors is increased toward infinity, the system may be referred to as primary-less. One primary-less system would be a system which can represent color using all the colors defining the boundary of the full gamut of all possible colors in nature, and thus represent all the colors within that full gamut of all possible colors in nature.
Collecting and directing light from a scene onto a sensor whose picture elements are overlaid with a color filter array arranged to divide each picture element into regions sensitive to each of the three or more primary colors photographically produces conventional digital three-primary and higher-order images. That is, a sensor is divided into picture elements, and the picture elements are further divided into three or more regions. The regions are each covered by a filter rendering each individual region sensitive to substantially one color. By one color, a single wavelength (or, inversely, frequency) of light might be meant, but in practical filters and systems one color may be a narrow band centered around a central wavelength, a broadband light having a principle observable color at the central wavelength either due to the energy being highest at or near the central wavelength, or due to averaging of the broadband light at the sensor (e.g. an observer's eye). A portion of a filtered broadband light source perceived or detected as “blue,” for example, may be at a discrete wavelength defined as “blue,” may cover a range of wavelengths having a distribution perceived or detected as “blue” due to averaging at the sensor, or may include a number of discrete spectral elements that when combined at the sensor are perceived or detected as “blue.” The visible spectrum includes wavelengths of about 380 nanometers (nm) through 800 nm. Broadband “red,” “green,” and “blue” filters roughly matching the sensitivity of human sight might cover bands of 615-675 nm, 510-560 nm, and 440-480 nm, respectively, for example. Narrowband filters for “red,” “green,” and “blue” might cover a few nm to a few tens of nm around the central values of 635 nm, 540 nm, and 460 nm. Popular color filter arrays for use in consumer and professional three-color systems include the Bayer array, the Fujifilm E×R array, the Fujifilm X-trans array, and various RGBW arrays. The Bayer array layout is illustrated in FIG. 1. In conventional sensors and color filter arrays, light of each primary color (± a few nm to a few tens of nm) from each part of a scene is collected and sensed by regions much smaller in area than the area of each picture element, since each picture element is divided into a number of regions at least equal to the number of primary colors required to represent the gamut. Alternatively, collecting and directing light from a scene onto film whose three or more layers are sensitive to, or filtered to receive three or more primary colors photographically produce conventional film-based three-primary and higher order images.
Conventional three-primary and higher-order images are projected or displayed by activating sources of light of the three or more primary colors in an arrangement that forms a two-dimensional viewing array of picture elements, each of which combines the three or more primary colors to produce a desired spot color at each of the projected or displayed picture element locations. As with the sensors for producing images represented by picture elements having three or more primary colors, such projection systems require displays with either spatial or temporal resolution, i.e., image bandwidth, substantially higher than the desired number of picture elements, to provide the requisite number of primary colors within each picture element. For example, each picture element may be divided either temporally or spatially into three or more parts, each part passing through a primary-color filter, which parts are then recombined into a single picture element. For example, in a flat panel display, each pixel is divided into three or more sub-pixels, each of which is a different primary color. In many conventional projection systems, though, the primary colors defining each pixel are separated either temporally, e.g., by a rotating color wheel spinning in front of the light source or different colors of LEDs blinking on and off in sequence, or spatially, e.g., by a beam-splitting filter system that separates the light source into three or more beams of different primary colors which then each shine onto a dedicated pixel array such as in a Digital Light Processing (DLP) projector before recombining again using a beam-combining system, or three or more separate light sources, each producing a different primary color, each shining onto a different pixel array before combining into a single image projection. By temporally separating the primary colors corresponding to each pixel, or by spatially separating them using beam splitting, the image bandwidth of the system is increased by a factor equal to the number of primary colors corresponding to each pixel. While each imaging device needs a resolution no greater than the resolution of the final image, the combined resolution is greater by a factor equal to the number of primaries by which the final image is represented. Such dividing and recombining may be achieved using rotating, segmented color wheels or beam splitters for high-, medium-, and low-pass filters—red, green, and blue—and beam-recombining reflectors. Alternatively, a high-bandwidth source of light can be projected through a film whose layers represent the combinations of three or more primary colors throughout a two-dimensional array representing the image.